pcie_bifurcation: Fetch bifurcation at a PCIe slot with hardcoded values

This will read a json config and return the bifurcation based on that.
It will read the configure file in a persistent file to see if it is
valid machine config and return the bifurcation information
accordingly.

For example,
If it is valid config, it will return 8x8 for PE1,3,4,6.

Tested:
Unit tests passed.

Physical Tests.

PE0 -> no bifurcation
PE1 -> x8x8

```
$ ipmitool raw 0x2e 0x32 0x79 0x2b 0x00 0x0f 0
 79 2b 00 0b 00

$ ipmitool raw 0x2e 0x32 0x79 0x2b 0x00 0x0f 1
 79 2b 00 0b 02 08 08
```

Change-Id: I44aefbfb26372f8bc0069343c8a6d07d3cf6f42d
Signed-off-by: Willy Tu <wltu@google.com>
diff --git a/test/pcie_bifurcation_unittest.cpp b/test/pcie_bifurcation_unittest.cpp
new file mode 100644
index 0000000..90e81e4
--- /dev/null
+++ b/test/pcie_bifurcation_unittest.cpp
@@ -0,0 +1,74 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "commands.hpp"
+#include "handler_mock.hpp"
+#include "helper.hpp"
+#include "pcie_bifurcation.hpp"
+
+#include <vector>
+
+#include <gtest/gtest.h>
+
+using ::testing::Return;
+
+namespace google
+{
+namespace ipmi
+{
+
+using testing::_;
+using ::testing::ContainerEq;
+
+TEST(PcieBifurcationCommandTest, InvalidRequest)
+{
+    std::vector<uint8_t> request = {};
+
+    HandlerMock hMock;
+    EXPECT_EQ(::ipmi::responseReqDataLenInvalid(),
+              pcieBifurcation(request, &hMock));
+}
+
+TEST(PcieBifurcationCommandTest, ValidRequest)
+{
+    std::vector<uint8_t> request = {5};
+    std::vector<uint8_t> expectedOutput = {4, 8, 1, 2};
+
+    HandlerMock hMock;
+    EXPECT_CALL(hMock, pcieBifurcation(5)).WillOnce(Return(expectedOutput));
+
+    auto reply = pcieBifurcation(request, &hMock);
+    auto result = ValidateReply(reply);
+    auto& data = result.second;
+
+    EXPECT_EQ(sizeof(struct PcieBifurcationReply) + expectedOutput.size(),
+              data.size());
+    EXPECT_EQ(SysOEMCommands::SysPCIeSlotBifurcation, result.first);
+    EXPECT_THAT(std::vector<uint8_t>(data.begin() + 1, data.end()),
+                ContainerEq(expectedOutput));
+}
+
+TEST(PcieBifurcationCommandTest, ReplyExceddedMaxValue)
+{
+    std::vector<uint8_t> request = {5};
+    std::vector<uint8_t> expectedOutput(64, 1);
+
+    HandlerMock hMock;
+    EXPECT_CALL(hMock, pcieBifurcation(5)).WillOnce(Return(expectedOutput));
+    EXPECT_EQ(::ipmi::responseInvalidCommand(),
+              pcieBifurcation(request, &hMock));
+}
+
+} // namespace ipmi
+} // namespace google